1. Technical Field of the Invention
The present invention relates to a safety or child resistant closure and container combination providing a stacking feature. More particularly, the present invention relates to a safety closure and container combination, wherein the safety closure and the container are each provided with at least one axial aligning surface which cooperates to transmit a stacking load from the top wall of the closure to the neck of a container in order to prevent biasing, child resistance, seal failure and/or other failure or unintended seal breach under stacking load conditions.
2. Description of the Related Art
It is well known in the prior art to sealingly affix a safety closure upon the neck portion of a container. However, after containers are filled and closed for the first time, they are frequently packed in stacks in boxes for shipment or are displayed in stacks for marketing purposes. Such stacked loading of the containers and closures subjects the packages to large vertical or axial loads which can distort and permanently deflect the biasing means or spring (mechanical spring, spring liner, etc.), the seal, and/or the sidewall of the closures to a position in which only a rotating force is required to remove the closure from the container thereby destroying the child resistant feature. Additionally, unintended breach of seal can expose the contents of the closure to the ambient environment spilling or spoiling the contents therein.
When manufacturers mass-produce containers and closures containing drugs, food, drink, and the like, the containers are usually shipped to distributors and vendors, for public consumption. In order to prepare the containers for shipping, the containers are often stacked in an axial or vertical manner and placed in boxes or crates in a space saving configuration. Throughout shipping and storage of the containers, they remain in this vertical configuration for various periods of time. The extended storage times often result in large axial loads being placed on the container closures for a long period of time, which is often not factored into their design. As a result of stacking large loads for extended periods of time, sealing gaskets located within the closures rupture or become disfigured; springs or biasing means loose their flexibility; and/or closures become disfigured or distorted, in turn causing the loss of the child resistant feature, leakage, spoilage, or destruction of the substance stored therein. Even unintended breach of a seal can cause destruction of the substance stored therein. Such substances often include, for example, a liquid, dry powder, or a plurality of pills, capsules, tablets or the like.
Various inventions use a container with a single thread and a small pitch to bear a stacking load. However there are various disadvantages inherent with these structures. First, a container or closure having a small pitch necessarily has a small target area for engagably starting the closure threads on the container threads. Secondly, machines used for installation of screw on closures often turn closures at a rate of about 500 RPM. This speed in combination with a small target area can lead to manufacturing difficulties and stripped threads. Thirdly, such a configuration is limited to threaded container and closure combinations and is not applicable to other closure retaining designs such as bayonet lug retaining means.
In view of the deficiencies in the known container and closure combinations, it is apparent that a closure and container combination is needed having top load seal protection characteristics or stacking feature as well as having a closure which is easy to install on the closure.